No abstract

Changes in the microstructure and phase content of beta alumina near the lowest possible β-Al2O3 to β-Al2O3 transform temperature were investigated through varying sintering temperature. Obvious microstructure varieties were observed in stabilized β/β alumina specimens following extended sintering treatments. The results show that there is a slightly lower temperature of 1150°C for nanometer precursor powder particles to transform into grains and for β-Al2O3 to convert into β-Al2O3.

Li/graphite fluoride (GFx) cells, with highest theoretical capacity in primary lithium batteries, high energy density, long shelf life, safety and a wide operating temperature, have been widely noticed during the past decades. However, the low electronic conductivity and discharge potential of Li/GFx cells obviously limited its applications. The key to improve the energy performance of Li/GFx cells is to increase the transportation ability of Li+ in cathode materials. Considering its high specific surface area, large bulk volume and layer spacing, Ketjenblack is used for preparing the cathode materials with highly stored energy. Based on gas-solid fluorination, we synthesized the fluorinated Ketjenblack (FKB). As the cathode materials of lithium batteries, electrochemical assay show that the lithium/FKB cells have a novel discharged voltage of 3V versus Li/Li+ electrode, and a special capacity near 800 mAh g-1. The lithium/FKB cells may be used for a new highly stored energy device.

Lithium/fluorinated carbon batteries (Li/CF), which have the highest theoretical capacity, long shelf life, a wide operating temperature, safety and non-pollution, have been becoming the best potential storage batteries. Bamboo charcoal with high specific surface area and large layer spacing is suitable for preparing the fluorinated carbon material. By means of ameliorating the preparation process and gas-solid fluorination, the moderate output fluorinated bamboo charcoal was synthesized. Used for the cathode material of lithium battery, it also reveals the novel discharged voltage of 3V versus Li/Li+ electrode and the special capacity over 800 mAh⋅g-1.

Pyrocarbons were obtained by heat-treatment of Ketjenblack at different temperature from 1000°C to 2400°C, and fluorinated in NF3atmosphere at 520°C to give CFxsamples with high fluorine content. The results indicate that the structure of both pyrocarbons and their derivative fluorides mainly depend on the heat-treatment temperature of raw carbon. The correlation between the electrochemical performance and the structure of pyrocarbon fluoride was discussed in detail. At an optimum condition, the yield of fluorination can come up to 90%, and the pyrocarbon fluoride, as cathode active material of lithium primary cell, gives an energy density up to 2200 Wh kg-1.